The Most Frequent Network Vulnerabilities Businesses Face

Top Network Security Vulnerabilities Businesses Must Fix in 2026

At Support Tree, we understand the critical role secure networks play in protecting business continuity, customer data, and company reputation.

Network security vulnerabilities are among the most common entry points cyber criminals exploit to gain unauthorised access, steal sensitive information, or disrupt operations.

This article outlines the most frequent network vulnerabilities and provides practical advice to help London-based organisations strengthen their security posture.

If you’re looking for professional guidance, our Managed IT Support Services include dedicated support for network security, risk assessments, and ongoing threat protection.

What Is a Network Vulnerability?

A network vulnerability is a flaw or weakness in a system’s design, implementation, or management that could be exploited to compromise confidentiality, integrity, or availability.

These vulnerabilities may arise from outdated software, human error, weak configurations, or inadequate policies.

For small and medium-sized businesses, particularly those without in-house cyber expertise, such weaknesses are often overlooked until an incident occurs.

Understanding these vulnerabilities is the first step toward building a resilient and secure IT environment.

The Five Most Common Network Vulnerabilities

1. Weak Password Policies

Passwords remain one of the most common network security vulnerabilities in cyber breaches.

Unfortunately, many organisations still rely on short, predictable passwords with low complexity, and often without multi-factor authentication (MFA) in place.

How to Improve Password Security:

• Enforce minimum password length and complexity standards.
• Encourage the use of passphrases (e.g., “CoffeeMugSunnyWindow”).
• Enable Multi-Factor Authentication (MFA) for all users, especially those with administrative access.
• Perform regular audits to detect and remediate weak or reused credentials.
• Educate employees through cybersecurity training and awareness sessions.

2. Default Login Credentials

Many devices, including routers, printers, and VoIP phones, are deployed with factory-default usernames and passwords. If not changed, these credentials are publicly accessible and easily exploited.

Securing Default Credentials:

• Replace default credentials immediately during device setup.
• Regularly audit your network for any devices still using manufacturer logins.
• Restrict device access with proper role-based controls.
• Train staff on the risks associated with default configurations.

At Support Tree, our Managed Cyber Security Services include configuration reviews and routine checks to ensure your infrastructure isn’t vulnerable to basic attacks.

3. Lack of Network Segregation

A flat network structure, where all devices are on the same segment, can allow attackers to move laterally once they’ve gained initial access.

Proper network segmentation helps contain potential breaches.

Steps to Improve Network Segregation:

• Separate guest networks from internal systems using VLANs.
• Limit inter-network communication on a strict need-to-access basis.
• Isolate critical systems such as finance or HR databases from general access.
• Use internal firewalls to monitor and restrict lateral movement.

Segmenting your network reduces the attack surface and ensures that one compromised endpoint doesn’t bring down the entire business.

4. Storing Data in Clear Text

Sensitive data such as passwords, personal records, or financial details should never be stored in unencrypted formats.

If an attacker gains access to your systems, clear-text data can be exfiltrated with minimal effort.

Protecting Sensitive Data:

• Store passwords in encrypted password managers.
• Use full-disk encryption and protect shared drives with access controls.
• Encrypt files stored in cloud services like Microsoft OneDrive.
• Implement role-based access and monitor permissions regularly.

If you’re unsure whether your data is protected, we can conduct a data security audit and help you implement secure storage policies.

5. Unsupported Operating Systems and Applications

Running legacy software that is no longer supported or updated is a significant risk.

Unsupported systems lack current security patches and are often targeted by attackers using known exploits.

How to Manage Legacy Systems:

• Identify and document all outdated systems and software.
• Plan upgrades before support deadlines (e.g., Windows 10 end-of-life in October 2025).
• Where replacement isn’t possible, isolate these systems and monitor activity closely.
• Apply virtual patching solutions as a temporary measure.

Support Tree’s Managed IT Support Services include patch management and software lifecycle planning to help businesses stay up to date and secure.

Building a Stronger Network Security Strategy

The vulnerabilities listed above represent just a few of the most common threats we see in London-based businesses.

By proactively addressing these areas, your organization can significantly reduce the risk of cyber attacks and improve resilience.

Key Actions to Take:

• Strengthen password and authentication policies.
• Eliminate default device credentials.
• Implement network segmentation.
• Encrypt all sensitive data.
• Retire or isolate outdated systems and applications.

Our team at Support Tree is here to help.

We provide tailored network security services and risk assessments designed specifically for SMBs.

Whether you’re looking to strengthen your current setup or build a security-first IT strategy from the ground up, we can support you.

Looking for support?

Contact us today to learn how we can help protect your organisation’s infrastructure, users, and data from common vulnerabilities.